The present invention relates generally to an injection pressure sensor and more particularly to an injection pressure sealing mechanism to minimize fuel leakage in the event of damage to the pressure sensor.
Injection pressure sensors (IPS) are well known in the automotive industry. Injection pressure sensors are commonly mounted directly to the fuel rail. IPS devices are used to monitor the pressure of the fuel within the fuel rail relative to the manifold pressure to assist in the regulation and control of the fuel injectors.
Performance issues alone do not govern the design of IPS devices. Modern automotive design is not only driven by cost and performance concerns, but also by other complications resulting from part failure. Systems within an automobile are often designed such that when failure occurs, safety issues or costly repairs do not occur. If these issues are not adequately addressed, the resulting costs and other complications can diminish customer satisfaction. Reduction in customer satisfaction is often highly undesirable.
Part failure must be considered in evaluating the design of an IPS device as well. IPS devices commonly are attached to the fuel rail on one end and are exposed to the manifold absolute pressure (MAP) on the other. In this way the pressure differential between the fuel and the manifold is determined and the fuel injector control can be varied accordingly. A variety of conditions, however, are known that can increase the pressure of the fuel to a point where it can damage the IPS. This increase in pressure can be brought on by a malfunctioning fuel pump, a vehicle crash, or another system failure within the automobile.
When extreme fuel pressure levels are reached, it the sensor within the IPS device can be damaged. If the sensor breaks, fuel can pass through the IPS device and enter the manifold. This is undesirable for a variety of reasons, since fuel can possibly escape outside the engine, or provide such an overly-rich fuel operating condition which can damage the engine.
It would therefore be desirable to have a design for an IPS that can be exposed to high fuel pressures and not be adversely affected or cause fuel leakage past the IPS.
It is therefore an object of the present invention to provide an injection pressure sensor that minimizes fluid leakage from a fluid source when the pressure sensor is damaged due to extremely high fluid pressure levels.
In accordance with the object of this invention a injection pressure sensor is provided which includes a sensor element in communication with a fluid source and additionally in communication with a pressure reference source. The sensor element measures the difference in pressure between the fluid source and the pressure reference source.
The injection pressure sensor further includes a plunger element positioned within the sensor body with an active position and an inactive position. If the sensor element becomes damaged and fluid from the fluid source enters the sensor body, the plunger element moves from its inactive position to its active position. When the plunger element is in the active position fluid from the fluid source is maintained within the sensor body.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.